This is where a woman is penetrated by three men with the penises in different combinations in the anus or vagina eg 2 in the vagina and 1 in the anus. Hence, quadrouple penetration would be relatively simple by stationing another penis in front of the woman's mouth.
The term is often confused with an "airtight seal" which is where all three orifices are filled with a penis.
Many are skeptical about this as not many women are able to accomodate such a volume plus the restrictions in space make it difficult, plus many men aiming to penetrate a woman would not enjoy the concept of grinding their penis against another man's. However, it has been seen in a small volume of porn films and in the Annabel Chong sex marathon.

That girl was a real dirty loose whore last night, we managed triple penetration!

When a girl participates in a sexual act which involves a cock in her mouth, a cock in her asshole, and a cock in her pussy all at once. Many females may find this degrading but I myself as a female find this act very satisfying. I feel my body, especially my pussy, was made for men to fuck, so the more the better. The act is especially satisfying if all men can manage to jizz in you simultaneously, so you can feel the jizz dripping into and pouring out of your cunt and asshole, and down your throat. Even more fun if a fourth friend joins in and can manage to fit his cock (two cocks) in your pussy as well. Can also mess around and insert different objects into the pussy and asshole while performing this act (i.e., beer bottles, cell phones, drumsticks, pencils, pens, dildos, hot dogs are all good ideas).

I love regular sex, but I'm really a kinky bitch who loves to be fucked in every fuckhole I have - triple penetration is the best. Being fucked in my pussy, asshole, and my mouth feels better than anything. The more cocks, the better. If a guy wants to invite his friends and have two cocks fuck your cunt, two cocks fuck your asshole, two cocks fuck your mouth, one cock fuck your tits, and then two cocks fucking your ear, let them! Seven is the most I've ever taken and it was pure heaven. Triple penetration is usually the most a beginner can take, though.

One of the favorite sex acts of a complete slut. The whore will beg to have all her wet holes filled at once. A slut loves to feel cocks pumping her mouth, pussy, and ass at the same time. She can't get enough and begs them to cum all over her dirty body.

I just saw a video of Kathy doing a triple penetration with 3 black guys. She is such a blonde slut. Ive never seen a woman over 50 get fucked like that. Her white mouth, pussy and ass were stuffed with black cock. She begged them to fuck her harder and use her like a white slut. "Fuck me, pump my married white pussy and ass" Kathy said into the camera. "I love being a whore for black cock". When the men were done shooting cum all over her body, Kathy started rubbing the cum into her skin and begging for more.